VNT Rabbit tuning: intercooler + more boost

[veeman]

>>There is a main bearing set available that has the 3rd main bearing separated from the thrust surfaces. It looks like this:

Ah... Ok.  I see what you mean.  The 5-cyl's I rebuilt had the separate thrust bearings, but the air-cooleds I did have the one piece bearings.  

I'm wondering whether the 1pc versus the separate bearings included with a kit is purely a cost issue...  Obviously they must be "interchangeable" but the factory had a preference, right?

[fspGTD]

The VNTD Rabbit engine was definitely rebuilt once during the previous ownership; we got the receipts for it.  It is hard to say how many miles ago it was done because the odometer was skipping (since then fixed.)  But it could very well be in the hundreds of thousands since the rebuild.  It was done by Tom Noble Engineworks in Ballard, WA.  This is the same guy who rebuilt the engine in my Rabbit GTD autocrosser (he has since retired and his business is gone) so I've probably got the same main bearings in it.

That is interesting Brendan about you remembering selling the separate thrust washer / main bearings while working at VW.  What I am seeing in ETKA and also what is pictured in Bentley seem to be the one-piece integrated main/thrust bearings.  So I am now curious what kind of bearing really did originally did come on these motors...  Certainly the "tangs" that hold the separate thrust washers are machined into the main bearing saddles (probably on all watercooled VW motors) so they could be updated easily.

As to what would make the bearing wear out like it did... I don't know but I suspect besides using the clutch while cranking, it could possibly be that they don't get installed right.  My local vw specialist engine builder was telling me about how he would set those one-piece integrated thrust/main bearings squarely into place by taking a dead blow hammer to each side of the crank with it installed but before the 3rd main cap was fully tightened.  It might help to square the thrust surfaces up to the crank and help them last longer.  Anyone heard of or use this procedure for installing the one-piece mains with the integrated thrust bearings?

Dr. Diesel has some bad things to say about the one-piece integrated thrust bearings here: http://www.vwdiesel.net/phpBB/viewtopic.php?t=399

[lord_verminaard]

Funny that Etka doesnt list the separate thrust washers until 87.  I'm pretty sure they are all the same size. (within similar engines that is)  I remember one customer called about a JH engine he was rebuilding and wanted the thrust washers from a later model.  Must have worked.

Brendan
84 Scirocco 8v
00 Camaro L36 M49

[larry104]

Can you please tell me  about your intake/air filter setup? I want to ditch the stock airbox on my '92 Eco and am looking for a replacement.   I also was thinking of installing an intercooler and a straight-thru exhaust (no cat).  Thank you.

[fspGTD]

It's a PRM air filter.  More info about it on this thread from the old GTD forum:
http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=291

[larry104]

Thank you. Great information.

[lord_verminaard]

Digging this one back up from the depths... Was browsing Bildon Motorsports site, and came across this:  http://www.bildon.com/catalog/DetailsList.cfm?ID=056198451SP&Nav=6

So the thrust washer problem is solved- and at $40 a set, not too bad really when you know you are getting good stuff.

Brendan
84 Scirocco 8v
00 Camaro L36 M49

[fspGTD]

VNT Rabbit update: it was down for a while due to another leaking headgasket.  The original cause of the headgasket leak (before the VNT turbo was added...) apparently wasn't fixed.

We believe to have found the culprit: the head was improperly rebuilt.  Although the deck measured perfectly flat, the cam bearings didn't  So it was warped but someone tried to fix it by maching the deck flat.  That's no good.

Since the head wasn't worth saving (it was naturally aspirated anyway...) It's now got a shiney, brand new aftermarket soid lifter head on it.  It was amazing how fresh and shiney the aluminum was!


Interestingly, check out how this head casting (not a genuine VW head, but still seemed very high quality...) has the extra "bulge" usually associated with the extra oil drain of a hydraulic head (This is a solid lifter head)


We used a 1.9lTD multi-layer steel headgasket.  No more worries about excessive boost pressure on a cold motor now.

It seems to be running very strongly and reliably!

We also drilled some extra holes in the water jacket to further improve cooling system reliability.  Details are posted in this thread:
http://vwdiesel.net/phpBB/viewtopic.php?t=4308

Another change made with the new head, was to try out a TDI cam profile.  Subjectively, it seems to give a bit more low-end torque.  It's running great (and good to have back running!)

Now... if I can just get my Rabbit GTD autocrosser back up and running...

[mvptrukin]

Nice work on the VNT project! I always wait for updates to see your next inovations. Where did you get the aftermarket cylinder head ? Is that one of the made in Spain cyl. heads? I haven't been able to find those anymore.
                                                                               Thanx,
                                                                                Pete

[RabbitJockey]

is there a post anywhere that talks about how to use a 1.9 head gasket?

[veeman]

Jake... that cylinder head sure does look nice.  Any info/prices on the source for those?  I just had a really bad day with my TD and will most likely be shopping for one.

I'd also be interested in the metal headgasket fitment.